Pusher



5. BV MARTN PUSHER Filed Aug. 26, 1944 Patented Jan. 3, 1950 PUSHER Stoddard B.- Martin, Cleveland, Ohio; Central National Bank of Cleveland, executor of said Stoddard B. Martin, deceased, assignor to Margaret J. Martin Application August Z6, 1944, Serial No. 551,317

7 Claims. 1

This invention relates to pushers for automatic screw machines and the like.

The principal object of this invention is to improve and simplify the installation and removal of work engaging pads in a pusher having a stronger stock gripping force n the forward, or stock advancing, stroke than on the retracting stroke. Other objects are to simplify and improve the arrangement and cooperation of a pusher and stock gripping pads by which the gripping force is increased on the advancing stroke and decreased on the retracting stroke. Other objects will appear in the following detailed description of preferred embodiments of the invention.

In the accompanying drawings:

Fig. 1 is a side elevation of a pusher, constructed in accordance with this invention, gripping a piece of stock;

Fig. 2 is a longitudinal section throughv the pusher on the line 2-2 of Fig. 1;

Fig. 3 is a cross section taken on the line 3-3 of Fig. 2;

Fig. 4 is a side elevation taken from the position indicated by the line 4-4 of Fig. 3 looking in the direction of the arrows; and

Fig. 5 is a longitudinal section through the pusher showing a different form of stock engaging pad.

Referring to the drawings, the pusher illustrated includes a shell I0 arranged to be connected, as by threads II, to the end of a pusher tube of the type slidably mounted within the collet tube of an automatic screw machine. The shell I0 is provided with longitudinal splits I2 extending inwardly from the front end of the pusher shell and terminating in drilled holes I3. Two splits I2 are shown in the drawings, but it will be understood that any desired number may be used. Ordinarily on smaller sizes two splits are employed and on larger sizes three or four splits. Near its forward end the shell I0 is formed internally with a tapered groove I4 extending from the shoulder I5 to the shoulder I6 and increasing in diameter toward the shoulder I6. The shell I Il is closed in after splitting and spring tempered so that the portions of the sheel separated by the splits constitute spring tongues having an inward set.

Work engaging pads I'I are arranged to be received in the groove I 4 of the shell Ill. In the embodiment illustrated three pads Il, each slightly shorter than one third (1/3) the circumference of the shell, are used with a relatively narrow key pad I8 in accordance with the arrangement disclosed and claimed in my copending application, Serial No. 494,641, filed July 14, 1933, now Patent No. 2,433,230. The combined circumferential length of the pads I1 and I 8 is such that when no stock is positioned in the pusher, the side edges of the pads are held in abutting relation by the 2 inwardly directed spring tension of the shell I0. When stock S is engaged in the pusher the edges of the pads are separated slightly as indicated at I 9 in Fig. 3, and the inner surfaces 20 of the pads then define a circle substantially equal in diameter to the diameter of the stock S.

The outer surfaces 2| of each of the pads I1 and of the pad I8 are tapered at the same angle as the bottom of the groove I4 so that when the pads are in position in the groove I4 their inner surfaces 20 are disposed axially. The axial length of the pads II and I8 is somewhat less than the axial distance between the shoulders I5 and I6 in the shell IIJ. Thus the pads are free to slide axially on the taper between the shoulders I5 and I6.

To insure that the pads I'I and I8 will alwaysv slip in the groove I4 in preference to slipping on the surface of the stock, in spite ofthe larger area of contact between the pads and the groove I4, the inner surfaces 2D of the pads are roughened so as to increase the friction between the pads and the stock. Preferably the pads are formed with teeth 22 consisting of circumferentially extending projections having substantially radial sides 23 disposed forwardly and sloping sides 24 disposed rearwardly.

With this arrangement the teeth 22 act to grip the bar strongly when the pusher moves forwardly, or to the right as seen i'n Fig. 2, and grip more lightly when the parts are moved rearwardly, or to the left as seen in Fig. 2.

The radial thickness of the pads and the angle of taper of the groove I4 are proportioned with respect to the stock S so that when the pads are moved against the shoulder I5 with the stock in place, the shell IIJ is spread to its original unsplit diameter. When the pads are moved forwardly and positioned against the shoulder I6 the shell ID is permitted to collapse a small amount, which may be on the order of about .020 of an inch per inch of diameterof the shell. The shell I0 is preferably made with a stronger spring tension' when the pads are gripping the stock and positioned against the shoulder I5 than the tension ordinarily used for spring pushers. When the pads are moved against the shoulder I6 the spring tension of the shell is relaxed, preferably to such,

an extent that the total spring tension is then substantially less than the tension normally used on spring pushers.

In operation the shell I0 is intermittently advanced to the right, as seen in Figs. 1 and 2, when the collet of the machine is open so as to advance a new length of stock through the collet. After the collet has closed to grip the stock the pusher is retracted to the left, as seen in Figs. 1 and 2, in position to advance a new length of stock. When the pusher moves to the right the frictional engagement of the teeth 22 against the Vtracting stroke..v

Vserting a' spreading t'oolj in the. slots' I2 and' stock exeeeds-the friction ofthe outerL surfaces of the pads'- IrV an'd' I8@ against; the bottom of the groove I4, so that the stock and pads remain stationary while the shell advances until the pads.` come in contact with the shoulder I5. At this Y 5 point the maximum spring tension of the shell? I0 is applied to the stock so thatthestock is then advanced through the remainder.offthestroleof; the pusher Without slippage.' Whenftheshelltllll Y is retracted the friction between the stock and l0 the pads again exceeds the friction between the pads and the groove I4, so thatth'epads'eremain stationary on the stock until they contactzthe= l shoulder I6. Thereafter the pads are caused to slide-.- rearwardly over. thefsurface of. theY stock under the minimumspring'tensionofthe sliellI Eli By' reason of''tlieJrelaxing.' ofi the tension'Y of! the shell' I Il" the. stocl -isi notmarred or scratchedI by the..retractingstroliebofthe. pusher' and the wear. on the inner surfaces ofi the padsvi's greatly. reduced. Scratchin'grof thestcckis further' avoided,.'in. the preferred form illustrated", by the slb'piigsids Zloftliejeeth' ZZQWHCh reduce. the giipbetweentle pads andlthe-sto'ckonrthe re- VA`sV disclosed. in my'aforesaid` copending` application Serial!l No; 494,641',vv the pads' can be readily remove/citfrom thev pusher.A shell by first tl'ier'eafter'removing"the" pads' I'I; which' arelth'en' 30 loose.in.the shell. For replacement therpadsillare placedinposit'on 'an'dthe pad I Si's then force'd between' the adjacent' side'. edges. of' two ofi' the pads' |12, spreading the entire assembly circumferentally la'gain'st'tneA tension; ofthe shell IIT.` To facilitate' this operationthe' pad" IB.' is nef'r'ably'forined" with' a slightly pointed rear end 25 Y Y Y A In order'to simplif'ythe remo'valof'the' pads, means may bepro'vided to prevent rotation. of tiieY padsiwitnin the'shell'. As'shownintFig; 4" this meansmay consist of a' spring; tonguel` formed in' the' wall of: the she'l'lby cuts 27. extendiig circumferentiallya sho'rt'. distance' from o'ne` sidi-r1 ofl o'n'e. ofthe' splits' I2. The tonguefZE Visthen pressed inwardlybeyond the inward' set of the main body of the shell Ill.'V Aned'geofone of the pads I1' next tothe' key( pad Illisflciref erably beveled offsli'ghtl'y,V asgindicated`v atLZS in Figs? 3andj4,.so that the'tongueiZt" may project into'A the. slfl'ell slightly and' abutVv at itsi end; one radial: side of" the key pad" I8. Y* The tongue 26 is'jformedlsoasito pointin' a direction oppcsite to' the' direction' oflrotation' of'. the stock .SL soY that rotationofithe stockis; transmittedzby the pad I8" andthe tongue 25' to. the' shell'L I and the pusher tube: With' this arrangement the padsV aref always; readily"Y accessible for." removal by si'n'iplyr pushing" the point ofY apscrew driver or tlieA like tlirouglithe7 slot I2'into engagement with tlieY keyepad, I8. ToI avoid"Y slippage of the screw driver" orother' tool used to' remove' the key pad, without increasing the" friction fof the pads in' the' shelli a smallE groove'V 29 maybe turnedv in' the outer surfaceofithepad's' IFandy I5: v

It will be apparent that the present invention not confined to the useA of a key pad' I8,Y as

A thep'ads II* may allfbe made the. samesize and maybe-removed in-the conventional` way by in-V spreading the sneu III open.

it is desired? to use'smoot'h surfaced gripping pads; as" forjexample when' feeding extremely' soft stock; theaarrangement shown inl 4 sembledinthe groove ILofgtheshell I0.in..place of theffpadslI and I8. Tliepads 3T'and38 have tapered outer surfaces fitting the groove III, but

- are sufficiently long axially to be confined between the shoulders I5 and I6. The thickness of "the pads for each particular size of stock is selected Vto give Vthedesired spring gripping pressure onthe stock. Thee-stock engaging faces 39 of the pads-may be smooth, as illustrated.

Although; the-foregoing description is necessarily of a detailed character, in order that the inventionY may b'e'lcompletely set forth, it is to be..understood that the specific terminology is not intended to be restrictive or confining, and that various rearrangements of parts and modifications' of detail vmaybe' resorted' toiwithout departing from the scopeor. spirit ofthe invention as herein'claimed".Y

I claim:

1`.A pusher comprising a resiliently'expansible shell h'avinga conical pad-engaging` surface on its inneri wall, an'dla' plurality of mutualIy'free stock-engaging pads` having; conical outer walls slidably engaging then conicalI surface on said shell; ther inner' stock-grippingsurfaces" of said pads being formed ilo-increase thefriction thereof against said" stock, and said'shell'being'tensioned inwardly to press the edges of sad pads into mutual contact circumferentially, such as to maintain the innergrippingsurfa'ces'of said pads centered inv the shell with: stock'removed' therefrom; v

Y 2. A pusher comprising a shell having slots extending intothe same `from its-front edge forming a plurality of' springit'ongues, saidtonguesk havingeconica'l pad-engaging surfaces on their inner walls, and a plurality of separate stockengaging pads having inner stock-gripping surfaces and conical' outer walls slidably engagingv the conical surfaces on saidspri'ng tonguesfVsaid Y tongues beingl tensioned` inwardly and pressing theed'gesof said pads into mutual circumferential engagement when no stock is gripped by the pads, such as to maintainthe sto'ckegripping'surfaces centered in theY shell with the stock removed therefrom, said? pads beingY separatedL circumferentiallyv and. pressed` against; thestock by said tongues when stockv is gripped* therein; thel area' of engagementv of said pads onsai'd tonguesexceeding the areaof engagement off'saidi pads on saidfr stock, thev inner surfaces` of; said padsbeing formedto increasethe frictionL thereof against saidtstock. Y

3. A pusher comprisingfaresiliently-expansible shell Having a groove formed oir the inner surface thereof with a conicalbottomwall andtopposed'endlwallsf, and a plurality of separate` stockengaging pads having-inner stock-gripping surfaces and conical outer wall'sV slidably engaging the conical bottom surface of saidgroove, said `shell being tensioned inwardly and resiliently pressing the edges of'said padsinto mutual circumferential engagement whenV no stock is gripped by therpads, suchlas to maintain' the stock-*gripping surfaces centeredin` the shellwith.

pads, the inner surfaces' of sai'dpads-beingiformed with teeth to increase-A thefricton thereoagainst;

said stock. Y Y

4. A pusher comprising aresiii'entlyeexpansible 75 shell having a' groove formedon the inner surface thereof with a conical bottom wall and opposed end walls, and a plurality of separate stockengaging pads having inner stock-gripping surfaces and conical outer walls slidably engaging the conical bottom surface of said groove, said shell being tensioned inwardly and resiliently pressing the edges of said pads into mutual circumferential engagement when no stock is gripped by the pads, such as to maintain the stock-gripping surfaces centered in the shell with the stock removed therefrom, said pads being separated circumferentially and pressed against the stock by said tongues when stock is gripped therein, the axial distance between the end walls of said groove exceeding the axial length of said pads, the inner surfaces of said pads being formed With teeth having relatively sharp edges pointed in the direction of maximum groove diameter to increase the friction thereof against said stock.

5. A pusher comprising a shell having slots extending into the same from its front edge forming a plurality of spring tongues, said tongues having tapering pad engaging surfaces on their inner walls, the larger diameter of said surfaces being arranged toward the front edge of said shell, a plurality of separate stock engaging pads having inner stock-gripping surfaces disposed within said tongues, said tongues having an inward set and resiliently pressing the edges of said pads together into mutual contact circumferentially such as to maintain the inner gripping surfaces of said pads centered in the shell when no stock is positioned within the pads, said pads having tapering outer walls slidably engaging the tapering surfaces on said spring tongues, abutments on said tongues and said pads limiting the axial sliding movement of said pads with respect to said tongues, and stock engaging surfaces on said pads arranged to be pressed into engagement with stock by said spring tongues, the friction of said pads on the stock exceeding the friction of said pads on said tongues.

6. A pusher for screw machines and the like comprising a longitudinally slotted shell, a plurality of segmental pads disposed within said shell and arranged to grip the stock, one of said pads being of less circumferential extent than others and adapted to be pressed radially inward to free the remaining pads for removal from said shell, and means for preventing rotation of said pads within said shell in the direction of rotation of the stock in the machine.

7. A pusher for screw machines and the like comprising a longitudinally slotted shell, a plurality of segmental pads disposed Within said shell and arranged to grip the stock, one of said pads being of less circumferential extent than others and adapted to be pressed radially inward to free the remaining pads for removal from said shell, and means for preventing rotation of said pads within said shell in the direction of rotation of the stock in the machine, said means comprising a tongue projecting into said shell from an edge of a slot therein and engaging said one pad.

STODDARD B. MARTIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,379,165 Burns et a1. May 24, 1921 1,561,040 Wheeler Nov. 10, 1925 1,842,036 Luers Jan. 10, 1932 1,937,236 Laughlin Nov. 28, 1933 2,299,972 Y Gallen et al Oct. 27, 1942 FOREIGN PATENTS Number Country Date L169,737 Great Britain Nov. 28, 1933 Certificate of Correction Patent No. 2,493,680 January 3, 1950 STODDARD B. MARTIN It is hereby certified that errors appear in the printed specication of the above numbered patent requiring correction as follows:

Column 6, line 34, list of references cited, for Jan. 10, 1932 read Jan. 19, 1982; line 40, for Nov. 28, 1933 read July Z9, 1.937;

and that the Said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 27th day of June, A. D. 1950.

[SNL] THOMAS F. MURPHY,

Assistant Oommz'sszoner of Patents. 

